Query:added_components

Returns all components of a specific class (or inheriting from it) that became part of a match for this query during the last call to ECS:update.

A component is considered part of a match when two conditions are met:

1. The component’s class or one of its parent classes is a requirement for this query.
2. One of the following events happen:
   • Component belongs to an entity which was just spawned and matches the query.
   • Component was just added to an existing entity, and was the missing piece for the entity to match the query.
   • Component was already on the entity. Another component was just added and made the entity match the query.
   • Entity was already matching the query. This component was just added and also happens to be one of the requested classes for this query.

Usage

query:added_components(class)

Arguments

Name	Type	Description
class	string or component class	Base class of the newly added components that will be returned, as a string or as a reference.

Returns

Name	Type	Description
components	table	A table where every key is an added Component. Table values are the entities owning these components.

Examples

local Poison = Class("Poison", crystal.Component);
local PoisonSystem = Class("PoisonSystem", crystal.System);

PoisonSystem.init = function(self)
  self.query = self:add_query({ "Poison" });
end

PoisonSystem.frame = function(self)
  for poison in pairs(self.query:added_components("Poison")) do
    print((tostring(poison:entity())) .. " just got poisoned");
  end
end